Singer/songwriter Taylor Swift sings out about what she did wrong in a relationship, but she is reticent about whom she wronged.

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By Brian Mansfield Special for USA TODAY

NASHVILLE  Taylor Swift is known for skewering callous boys in her songs. On Back to December, a new song released today on iTunes, she sets her sites on a new target. Herself.

"It's the first time I've ever apologized in song," says the 20-year-old singer. "It's the first time I've ever admitted guilt in my music."

In the strings-laden, melancholy ballad, Swift expresses regret over the way she ended a romantic relationship. At one point, she sings, "This is me, swallowing my pride, standing in front of you, saying I'm sorry for that night."

Swift says she based the song on a conversation she had with the guy about whom she's singing. "It's not loosely based," she says. "It's almost word-for-word. It is a song and a conversation that needed to happen, because I don't want to hurt people. If you unintentionally do so, you've got to make that better."

Is Swift's Valentine's Day co-star Taylor Lautner the object of the song? The two briefly went out late last year, and Swift recently told Glamour magazine that they are still friends.

But Swift won't go so far as to say that Back to December is about Lautner.

"I feel so comfortable singing about these details and these relationships and listing times, dates, details, names," she says. "But when it comes to an interview and they say, 'Are you dating this person?' or 'Did you date this person?' or 'What's your current relationship status?' I suddenly feel very shy.

"It's such an interesting little quirk. It's like, 'Obviously, you're writing songs about your life and you're almost admitting to these things.' But when it actually comes time to talk about them in an interview, I get pretty shy and coy about it."

Back to December is the third song made available from Speak Now, the follow-up to Swift's seven-times-platinum 2008 album Fearless. Single Mine already has sold more than 1 million downloads, and the title track made its debut at No. 1 on iTunes last week. Before the album comes out Oct. 25, Swift will release two more tracks: Mean (on Oct. 18) and The Story of Us (Oct. 22).

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